Picosecond near-infrared excited transient Raman spectra of β-carotene in the excited S2 state: Solvent effects on the in-phase CC stretching band and vibronic coupling

Picosecond time-resolved Raman spectra of β-carotene in the excited S2 (1Bu+) state have been obtained in resonance with its near-infrared transient absorption. The Raman band due to the in-phase CC stretching mode of β-carotene in the S2 state has been observed at about 1550 cm−1. The solvent effects on this band are discussed in comparison with the previous results on the corresponding bands in the ground S0 (1Ag-) state and the excited S1 (2Ag-) state.